1. Field of the Invention
The present invention relates to an endoscope in which a rigid portion body on the distal end portion of an elongated insertion section to be inserted into a body cavity has mounting holes in which optical members of an observation optical system and an illumination optical system are mounted.
2. Description of the Related Art
In Jpn. Pat. Appln. KOKAI Publication No. 2002-85326, for example, a technique is described for fixing an optical member to a cover member that is provided independently of a rigid portion body on the distal end portion of an insertion section of an endoscope. According to this technique, the cover member having an opening is located on the distal end portion of the insertion section to hold the distal end face of the optical member in an exposed state. The diameter of the opening of the cover member on its one side is larger than the diameter on the other side, that is, the opening is tapered. The surface of the cover member which has the larger opening diameter is opposed to the proximal end side of the insertion section. The optical member has a tapered shape such that it is mounted in the tapered opening. Thus, the optical member can be prevented from slipping off the cover member.
The rigid portion body of the endoscope described above is formed having an opening in which an integrated unit that combines the optical member and a frame on the distal end portion of the insertion section is located. The optical member is firmly soldered or brazed to the frame. The cover member has a small hole in its distal end face. The diameter of the small hole is less than the largest diameter of the integrated unit. A large hole having a larger diameter than that of the small hole is formed in a position a little closer to the proximal end side of the insertion section than the distal end face of the cover member. The small and large holes are tapered and linked together. The optical member of the unit is tapered to mount the tapered cover member. If the integrated unit is inserted into the cover member from its proximal end side and fixed the optical member is prevented from being disengaged in a forward direction from the distal end face of the cover member.